CVE Vulnerabilities

CVE-2021-40449

Use After Free

Published: Oct 13, 2021 | Modified: Jul 24, 2024
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
4.6 MEDIUM
AV:L/AC:L/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu

Win32k Elevation of Privilege Vulnerability

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Name Vendor Start Version End Version
Windows_10_1507 Microsoft * 10.0.10240.19086 (excluding)
Windows_10_1607 Microsoft * 10.0.14393.4704 (excluding)
Windows_10_1809 Microsoft * 10.0.17763.2237 (excluding)
Windows_10_1909 Microsoft * 10.0.18363.1854 (excluding)
Windows_10_2004 Microsoft * 10.0.19041.1288 (excluding)
Windows_10_20h2 Microsoft * 10.0.19041.1288 (excluding)
Windows_10_21h1 Microsoft * 10.0.19041.1288 (excluding)
Windows_11 Microsoft * *
Windows_11_21h2 Microsoft * 10.0.22000.258 (excluding)
Windows_7 Microsoft –sp1 (including) –sp1 (including)
Windows_8.1 Microsoft - (including) - (including)
Windows_rt_8.1 Microsoft - (including) - (including)
Windows_server_2004 Microsoft * 10.0.19041.1288 (excluding)
Windows_server_2008 Microsoft –sp2 (including) –sp2 (including)
Windows_server_2008 Microsoft r2-sp1 (including) r2-sp1 (including)
Windows_server_2012 Microsoft - (including) - (including)
Windows_server_2012 Microsoft r2 (including) r2 (including)
Windows_server_2016 Microsoft * 10.0.14393.4704 (excluding)
Windows_server_2019 Microsoft * 10.0.17763.2237 (excluding)
Windows_server_2022 Microsoft * 10.0.20348.288 (excluding)
Windows_server_20h2 Microsoft * 10.0.19042.1288 (excluding)

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References